We have 7 billion people on this planet. It’s not that there’s not enough room on this planet for 7 billion people, it’s that the energy needs for 7 billion people are 7 billion people’s worth of energy needs, as opposed to, say, 2 billion. Imagine how much pollution would be in the air and the oceans if there were only 2 billion people putting it in? So yeah, we’re already overpopulated.